U.S. Pat. No. 6,866,769 illustrates a stud having a 12 point drive head and a flange made from a less malleable metal such as a powder metal nickel alloy.
U.S. Pat. No. 4,625,260, FIGS. 11-14, illustrate fasteners which utilize threaded studs with flanges and a knurled or serrated base portion adjacent the flange which is force-fitted or swaged into a hole in a mounting for heat dissipation purposes. See, column 5, lines 46 to col. 6, line 57.
FIG. 1 is a perspective view 100 of the prior art 4-tooth automation nut (fastener) inserted into and through the surface 101A of the plastic substrate 120. The device is referred to as an automation nut. FIG. 1 illustrates the barrel 102 of the prior art fastener protruding through the substrate 120. A counterbore 111 within the barrel 102 is shown proximate the second end 103 of the fastener. Shards 104 are caused by teeth of the fastener jammed forcefully into the substrate and project upwardly in proximity to the barrel 102. Protrusions 105 project upwardly from the surface 101A of the substrate 120 and are often discolored. The substrate may be plastic, wood, hard or soft plywood or pressboard. Nominally, the substrate thickness is 0.1875 to 1 inch. However, any size substrate may be used.
FIG. 1A is a cross-sectional view 100A taken along the line 1A-1A of FIG. 1 illustrating the prior art automation nut inserted into a plastic substrate 120. Internal threads 112 and flange 114 are illustrated in this view. Shards 104 extend upwardly as viewed in FIG. 1A above teeth 115, 117. Still referring to FIG. 1A, the upper surface 109 of the outer gripping portion 106 deforms the plastic above surface 109 as indicated by reference numeral 142. Reference numeral 141 represents distortion in proximity to the teeth 115, 117. Distortion of the plastic substrate along the fastener is illustrated by reference numerals 141 and 142. Protrusions 105 occur as illustrated in FIG. 1A along with attendant discolorations in the plastic substrate 120. The lower surface 101B of substrate 120 is illustrated in FIG. 1A.
The fastener of FIGS. 1 and 1A is secured to a substrate and then another device such as a bolt having external threads mates with the internal threads 112 for locking securement. Several methods of locking the externally threaded stud may be used. For example, nylon locking rings, metal locking rings, and deformation of the threads may be employed to insure that the fastener connection does not become loose.
FIG. 1B is a side view 100B of the prior art automation nut illustrating the flange 114 and teeth 115, 116 and 118 of the gripping portion 106. The height of the gripping portion 106 is also illustrated in FIG. 1B and is nominally 0.17 inches above the flange 114. The flange 114 is nominally 0.08 inches thick and the overall length or height of the automation nut is 0.625 inches. FIG. 1C is an end view 100C of the prior art automation nut and the teeth 115-118 are readily viewed. Further, FIG. 1C indicates a relatively large surface 109 of the gripping portion 106 and it is that surface which engages the substrate as the automation nut is forcefully shoved into the substrate. Referring to FIG. 1C, the distance between the outermost portions of teeth 115 and 117 is nominally 0.52 inches.
FIG. 1D is a perspective view 100D of the prior art automation nut illustrating the sharp squared teeth 115, 118, and 117 of the nut. Again, the surface area 109 of the gripping portion 106 is viewed well in FIG. 1D.
FIG. 1E is a perspective view 100E of the prior art automation nut shown positioned for insertion into the bore 130 of the plastic substrate 120. The bore is nominally 0.375 inches in diameter and the outside diameter of the barrel 111 is nominally 0.371 inches so that it may slidingly fit within the bore 130. Bore 131 in wood is the same diameter as bore 130. Essentially, the automation nut and its generally square-shaped gripping portion 106 are force-fitted along the arrow labeled F into a round hole or cylinder 130. Since the square-shaped gripping portion 106 of the automation nut is substantially differently shaped than its cylindrically-shaped bore 130 and since the distance from the apex of tooth 115 to the apex of tooth 117 is 0.52 inches, deformation of the plastic substrate 120 occurs. FIG. 1E represents the state before the automation nut is force fit into the bore and FIGS. 1 and 1A represent the result of force fitting the automation nut into the bore 130.
FIG. 1F is an enlarged view 100F of the prior art automation nut similar to FIG. 1 with the barrel flared to form a lip 111A thus securing the automation nut to the plastic substrate 120. It will be noticed that the flared barrel is somewhat distorted and non-symmetrical due to folding the lip 111A over the shards 104 and the protrusions 105. When the barrel 102 is flared the protrusions and shards prevent the barrel from folding smoothly and uniformly with respect to the bore 130 through the substrate 120.
FIG. 1G is a cross-sectional view 100G taken along the lines 1G-1G of FIG. 1F. A gap 150 between the surface 101A and the lip 111A is illustrated in FIG. 1G. Deformation of the plastic substrate 120 is caused by forcing the surface 109 and the teeth 115, 117 of the gripping portion 106 of the automation nut into the bore 130 of the substrate. Bore 130 has a diameter (0.375 inches) slightly larger than the outside diameter of the barrel 102 (0.371 inches) but substantially smaller than the distance between the teeth 115 and 117 (0.52 inches). Thus, as the automation nut is forced into the bore 130 the surface 109 above teeth 115, 117 engage and deform the plastic substrate 120 as indicated by reference numerals 141, 142. See FIG. 1H, a cross-sectional view 100H of the bore 130 through the plastic substrate prior to insertion of the prior art automation nut therein.
FIG. 1I is a cross-sectional view 1001 similar to FIG. 1G illustrating a barrel flared over deformed portions 141A, 142A of a wooden substrate 121. The deformed portions include splinters and broken wood fibers. Substrate 121 may be pressboard or particle board or it may be virgin wood. FIG. 1J is a cross-sectional view 110J of the bore through the wooden substrate 121 prior to insertion of the prior art automation nut therein.
FIG. 1K is a perspective view 100K of another prior art automation nut wherein the gripping portion 160 does not project very far from surface 113 of the flange 114 nor does barrel 162 extend upwardly very far as compared to the example illustrated in FIGS. 1B-D. One of the problems with the prior art is that the gripping portion having 4 teeth is difficult to manufacture using the cold headed process. The gripping portion 160 with 4 teeth, due to cold heading manufacturing problems, results in beveled teeth 161, 165, and 166. This is especially true when an automation nut as shown by way of example in FIG. 1K is manufactured for insertion into a relatively thin substrate. It is believed that the beveled edges of the teeth reduce the gripping ability resulting in a lower torque spin out.